Americans who want their cities to be "sanctuaries" for violators of federal law might properly go a step further and declare themselves free of ALL federal law. If one can selectively nullify a U.S. law, why not nullify the whole package? Including the U.S. Constitution.
Sounds absurd, doesn't it?
Is it any less absurd to rob your fellow citizens of the protection of a law that penalizes people who sneak into our country, or enter by deceit, or violate the terms of legal visas?
If you want people to have legal sanctuary who enter this way, shouldn't you make your case to the body that has jurisdiction over such questions - the United States Congress?
If you won't do that, will you at least have concern for your neighbors? I mean, stop asking state and local governments to encourage violation of federal law. They are authorities charged with protecting us, your neighbors. What makes it right to endanger your neighbors to indulge your philosophical or political opinion?